Global positioning system (GPS) is a constellation of Earth-orbiting satellites. A GPS receiver may analyze high-frequency, low-power radio signals from GPS satellites and employ multiple dimensional trilateration to obtain position, velocity and time information. As a result, GPS recievers may be employed in a variety of applications to aid in navigation and the like. One type of application is the use of GPS receivers in military applications, such as handheld and munitions applications.
A defense to GPS enabled military applications is transmission of a jamming signal. A jamming signal with enough power and suitable temporal and spectral signature causes interference and may deny the use of GPS in a particular area. In response to this threat, GPS receivers employ anti-jamming signal (anti-jam) technology to cancel the interference caused by the jamming signal and aid in reception of GPS signals.
There are several limitations of conventional anti-jam systems. One problem with conventional anti-jam systems is the form factor associated with the implementation. Conventional digital anti-jam systems are not suitable for placement in size constrained applications, such as handheld receivers and munitions applications. Additionally, conventional anti-jam systems require a substantial amount of power.
Referring to FIG. 1, an embodiment of an anti-jam system 100 known to the art is shown. Typically, anti-jam system 100 includes a four element antenna, four channel radio frequency (RF) downconverter 120, an analog to digital converter 130, covariance generation 140, a processor 150 and weight application 160. Processor 150 calculates adaptive weights based on a covariance matrix from covariance generation 140. The covariance matrix refers to a matrix whose elements are the cross-correlations between elements of an antenna. With four elements, a processor is necessary for calculation of the adaptive weights. The processor and four channel RF downconverter 120 require a substantial amount of power. Additionally, the covariance generation 140 and weight application 160 supporting a four channel anti-jam system contribute significantly to hardware complexity.
Consequently, it would be advantageous if an anti-jam system could be manufactured in a form factor for implementation within size-constrained applications and required less power.